ошибка: FRM47337 Tree node label can not be null
при выполнении скрипта
DECLARE
Itree ITEM;
top_node Ftree.Node;
new_node Ftree.Node;
i_value VARCHAR2(30);
BEGIN
Itree := Find_Item('tree_block.tree_item ');
new_node := Ftree.Add_Tree_Node(Itree, Ftree.ROOT_NODE,
Ftree.PARENT_OFFSET, Ftree.LAST_CHILD,
Ftree.EXPANDED_NODE, i_value, NULL, i_value);
END;